code: def test_pickle_roundtrip(self):
      a = sentinel("a")
      self.assertIs(loads(dumps(a)), a)
  
file_path: catalyst/tests/utils/test_sentinel.py
imports: from copy import copy, deepcopy
  from pickle import loads, dumps
  from unittest import TestCase
  from weakref import ref
  from catalyst.utils.sentinel import sentinel
label_desc: Use image node_id 10 for calling the SentinelTestCase obj's underlying member method code with example usage: obj.test_pickle_roundtrip() without return types